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Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -08001/*
2 * Hardware spinlock framework
3 *
4 * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
5 *
6 * Contact: Ohad Ben-Cohen <ohad@wizery.com>
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 as published
10 * by the Free Software Foundation.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 */
17
18#define pr_fmt(fmt) "%s: " fmt, __func__
19
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/spinlock.h>
23#include <linux/types.h>
24#include <linux/err.h>
25#include <linux/jiffies.h>
26#include <linux/radix-tree.h>
27#include <linux/hwspinlock.h>
28#include <linux/pm_runtime.h>
Juan Gutierrez93b465c2011-09-06 09:30:16 +030029#include <linux/mutex.h>
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -080030
31#include "hwspinlock_internal.h"
32
33/* radix tree tags */
34#define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */
35
36/*
37 * A radix tree is used to maintain the available hwspinlock instances.
38 * The tree associates hwspinlock pointers with their integer key id,
39 * and provides easy-to-use API which makes the hwspinlock core code simple
40 * and easy to read.
41 *
42 * Radix trees are quick on lookups, and reasonably efficient in terms of
43 * storage, especially with high density usages such as this framework
44 * requires (a continuous range of integer keys, beginning with zero, is
45 * used as the ID's of the hwspinlock instances).
46 *
47 * The radix tree API supports tagging items in the tree, which this
48 * framework uses to mark unused hwspinlock instances (see the
49 * HWSPINLOCK_UNUSED tag above). As a result, the process of querying the
50 * tree, looking for an unused hwspinlock instance, is now reduced to a
51 * single radix tree API call.
52 */
53static RADIX_TREE(hwspinlock_tree, GFP_KERNEL);
54
55/*
Juan Gutierrez93b465c2011-09-06 09:30:16 +030056 * Synchronization of access to the tree is achieved using this mutex,
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -080057 * as the radix-tree API requires that users provide all synchronisation.
Juan Gutierrez93b465c2011-09-06 09:30:16 +030058 * A mutex is needed because we're using non-atomic radix tree allocations.
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -080059 */
Juan Gutierrez93b465c2011-09-06 09:30:16 +030060static DEFINE_MUTEX(hwspinlock_tree_lock);
61
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -080062
63/**
64 * __hwspin_trylock() - attempt to lock a specific hwspinlock
65 * @hwlock: an hwspinlock which we want to trylock
66 * @mode: controls whether local interrupts are disabled or not
67 * @flags: a pointer where the caller's interrupt state will be saved at (if
68 * requested)
69 *
70 * This function attempts to lock an hwspinlock, and will immediately
71 * fail if the hwspinlock is already taken.
72 *
73 * Upon a successful return from this function, preemption (and possibly
74 * interrupts) is disabled, so the caller must not sleep, and is advised to
75 * release the hwspinlock as soon as possible. This is required in order to
76 * minimize remote cores polling on the hardware interconnect.
77 *
78 * The user decides whether local interrupts are disabled or not, and if yes,
79 * whether he wants their previous state to be saved. It is up to the user
80 * to choose the appropriate @mode of operation, exactly the same way users
81 * should decide between spin_trylock, spin_trylock_irq and
82 * spin_trylock_irqsave.
83 *
84 * Returns 0 if we successfully locked the hwspinlock or -EBUSY if
85 * the hwspinlock was already taken.
86 * This function will never sleep.
87 */
88int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
89{
90 int ret;
91
92 BUG_ON(!hwlock);
93 BUG_ON(!flags && mode == HWLOCK_IRQSTATE);
94
95 /*
96 * This spin_lock{_irq, _irqsave} serves three purposes:
97 *
98 * 1. Disable preemption, in order to minimize the period of time
99 * in which the hwspinlock is taken. This is important in order
100 * to minimize the possible polling on the hardware interconnect
101 * by a remote user of this lock.
102 * 2. Make the hwspinlock SMP-safe (so we can take it from
103 * additional contexts on the local host).
104 * 3. Ensure that in_atomic/might_sleep checks catch potential
105 * problems with hwspinlock usage (e.g. scheduler checks like
106 * 'scheduling while atomic' etc.)
107 */
108 if (mode == HWLOCK_IRQSTATE)
109 ret = spin_trylock_irqsave(&hwlock->lock, *flags);
110 else if (mode == HWLOCK_IRQ)
111 ret = spin_trylock_irq(&hwlock->lock);
112 else
113 ret = spin_trylock(&hwlock->lock);
114
115 /* is lock already taken by another context on the local cpu ? */
116 if (!ret)
117 return -EBUSY;
118
119 /* try to take the hwspinlock device */
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300120 ret = hwlock->bank->ops->trylock(hwlock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800121
122 /* if hwlock is already taken, undo spin_trylock_* and exit */
123 if (!ret) {
124 if (mode == HWLOCK_IRQSTATE)
125 spin_unlock_irqrestore(&hwlock->lock, *flags);
126 else if (mode == HWLOCK_IRQ)
127 spin_unlock_irq(&hwlock->lock);
128 else
129 spin_unlock(&hwlock->lock);
130
131 return -EBUSY;
132 }
133
134 /*
135 * We can be sure the other core's memory operations
136 * are observable to us only _after_ we successfully take
137 * the hwspinlock, and we must make sure that subsequent memory
138 * operations (both reads and writes) will not be reordered before
139 * we actually took the hwspinlock.
140 *
141 * Note: the implicit memory barrier of the spinlock above is too
142 * early, so we need this additional explicit memory barrier.
143 */
144 mb();
145
146 return 0;
147}
148EXPORT_SYMBOL_GPL(__hwspin_trylock);
149
150/**
151 * __hwspin_lock_timeout() - lock an hwspinlock with timeout limit
152 * @hwlock: the hwspinlock to be locked
153 * @timeout: timeout value in msecs
154 * @mode: mode which controls whether local interrupts are disabled or not
155 * @flags: a pointer to where the caller's interrupt state will be saved at (if
156 * requested)
157 *
158 * This function locks the given @hwlock. If the @hwlock
159 * is already taken, the function will busy loop waiting for it to
160 * be released, but give up after @timeout msecs have elapsed.
161 *
162 * Upon a successful return from this function, preemption is disabled
163 * (and possibly local interrupts, too), so the caller must not sleep,
164 * and is advised to release the hwspinlock as soon as possible.
165 * This is required in order to minimize remote cores polling on the
166 * hardware interconnect.
167 *
168 * The user decides whether local interrupts are disabled or not, and if yes,
169 * whether he wants their previous state to be saved. It is up to the user
170 * to choose the appropriate @mode of operation, exactly the same way users
171 * should decide between spin_lock, spin_lock_irq and spin_lock_irqsave.
172 *
173 * Returns 0 when the @hwlock was successfully taken, and an appropriate
174 * error code otherwise (most notably -ETIMEDOUT if the @hwlock is still
175 * busy after @timeout msecs). The function will never sleep.
176 */
177int __hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to,
178 int mode, unsigned long *flags)
179{
180 int ret;
181 unsigned long expire;
182
183 expire = msecs_to_jiffies(to) + jiffies;
184
185 for (;;) {
186 /* Try to take the hwspinlock */
187 ret = __hwspin_trylock(hwlock, mode, flags);
188 if (ret != -EBUSY)
189 break;
190
191 /*
192 * The lock is already taken, let's check if the user wants
193 * us to try again
194 */
195 if (time_is_before_eq_jiffies(expire))
196 return -ETIMEDOUT;
197
198 /*
199 * Allow platform-specific relax handlers to prevent
200 * hogging the interconnect (no sleeping, though)
201 */
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300202 if (hwlock->bank->ops->relax)
203 hwlock->bank->ops->relax(hwlock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800204 }
205
206 return ret;
207}
208EXPORT_SYMBOL_GPL(__hwspin_lock_timeout);
209
210/**
211 * __hwspin_unlock() - unlock a specific hwspinlock
212 * @hwlock: a previously-acquired hwspinlock which we want to unlock
213 * @mode: controls whether local interrupts needs to be restored or not
214 * @flags: previous caller's interrupt state to restore (if requested)
215 *
216 * This function will unlock a specific hwspinlock, enable preemption and
217 * (possibly) enable interrupts or restore their previous state.
218 * @hwlock must be already locked before calling this function: it is a bug
219 * to call unlock on a @hwlock that is already unlocked.
220 *
221 * The user decides whether local interrupts should be enabled or not, and
222 * if yes, whether he wants their previous state to be restored. It is up
223 * to the user to choose the appropriate @mode of operation, exactly the
224 * same way users decide between spin_unlock, spin_unlock_irq and
225 * spin_unlock_irqrestore.
226 *
227 * The function will never sleep.
228 */
229void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
230{
231 BUG_ON(!hwlock);
232 BUG_ON(!flags && mode == HWLOCK_IRQSTATE);
233
234 /*
235 * We must make sure that memory operations (both reads and writes),
236 * done before unlocking the hwspinlock, will not be reordered
237 * after the lock is released.
238 *
239 * That's the purpose of this explicit memory barrier.
240 *
241 * Note: the memory barrier induced by the spin_unlock below is too
242 * late; the other core is going to access memory soon after it will
243 * take the hwspinlock, and by then we want to be sure our memory
244 * operations are already observable.
245 */
246 mb();
247
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300248 hwlock->bank->ops->unlock(hwlock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800249
250 /* Undo the spin_trylock{_irq, _irqsave} called while locking */
251 if (mode == HWLOCK_IRQSTATE)
252 spin_unlock_irqrestore(&hwlock->lock, *flags);
253 else if (mode == HWLOCK_IRQ)
254 spin_unlock_irq(&hwlock->lock);
255 else
256 spin_unlock(&hwlock->lock);
257}
258EXPORT_SYMBOL_GPL(__hwspin_unlock);
259
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300260static int hwspin_lock_register_single(struct hwspinlock *hwlock, int id)
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800261{
262 struct hwspinlock *tmp;
263 int ret;
264
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300265 mutex_lock(&hwspinlock_tree_lock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800266
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300267 ret = radix_tree_insert(&hwspinlock_tree, id, hwlock);
268 if (ret) {
269 if (ret == -EEXIST)
270 pr_err("hwspinlock id %d already exists!\n", id);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800271 goto out;
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300272 }
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800273
274 /* mark this hwspinlock as available */
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300275 tmp = radix_tree_tag_set(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800276
277 /* self-sanity check which should never fail */
278 WARN_ON(tmp != hwlock);
279
280out:
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300281 mutex_unlock(&hwspinlock_tree_lock);
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300282 return 0;
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800283}
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800284
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300285static struct hwspinlock *hwspin_lock_unregister_single(unsigned int id)
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800286{
287 struct hwspinlock *hwlock = NULL;
288 int ret;
289
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300290 mutex_lock(&hwspinlock_tree_lock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800291
292 /* make sure the hwspinlock is not in use (tag is set) */
293 ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
294 if (ret == 0) {
295 pr_err("hwspinlock %d still in use (or not present)\n", id);
296 goto out;
297 }
298
299 hwlock = radix_tree_delete(&hwspinlock_tree, id);
300 if (!hwlock) {
301 pr_err("failed to delete hwspinlock %d\n", id);
302 goto out;
303 }
304
305out:
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300306 mutex_unlock(&hwspinlock_tree_lock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800307 return hwlock;
308}
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300309
310/**
311 * hwspin_lock_register() - register a new hw spinlock device
312 * @bank: the hwspinlock device, which usually provides numerous hw locks
313 * @dev: the backing device
314 * @ops: hwspinlock handlers for this device
315 * @base_id: id of the first hardware spinlock in this bank
316 * @num_locks: number of hwspinlocks provided by this device
317 *
318 * This function should be called from the underlying platform-specific
319 * implementation, to register a new hwspinlock device instance.
320 *
321 * Should be called from a process context (might sleep)
322 *
323 * Returns 0 on success, or an appropriate error code on failure
324 */
325int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev,
326 const struct hwspinlock_ops *ops, int base_id, int num_locks)
327{
328 struct hwspinlock *hwlock;
329 int ret = 0, i;
330
331 if (!bank || !ops || !dev || !num_locks || !ops->trylock ||
332 !ops->unlock) {
333 pr_err("invalid parameters\n");
334 return -EINVAL;
335 }
336
337 bank->dev = dev;
338 bank->ops = ops;
339 bank->base_id = base_id;
340 bank->num_locks = num_locks;
341
342 for (i = 0; i < num_locks; i++) {
343 hwlock = &bank->lock[i];
344
345 spin_lock_init(&hwlock->lock);
346 hwlock->bank = bank;
347
Shinya Kuribayashi476a7eeb2012-07-07 13:37:42 +0300348 ret = hwspin_lock_register_single(hwlock, base_id + i);
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300349 if (ret)
350 goto reg_failed;
351 }
352
353 return 0;
354
355reg_failed:
356 while (--i >= 0)
Shinya Kuribayashi476a7eeb2012-07-07 13:37:42 +0300357 hwspin_lock_unregister_single(base_id + i);
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300358 return ret;
359}
360EXPORT_SYMBOL_GPL(hwspin_lock_register);
361
362/**
363 * hwspin_lock_unregister() - unregister an hw spinlock device
364 * @bank: the hwspinlock device, which usually provides numerous hw locks
365 *
366 * This function should be called from the underlying platform-specific
367 * implementation, to unregister an existing (and unused) hwspinlock.
368 *
369 * Should be called from a process context (might sleep)
370 *
371 * Returns 0 on success, or an appropriate error code on failure
372 */
373int hwspin_lock_unregister(struct hwspinlock_device *bank)
374{
375 struct hwspinlock *hwlock, *tmp;
376 int i;
377
378 for (i = 0; i < bank->num_locks; i++) {
379 hwlock = &bank->lock[i];
380
381 tmp = hwspin_lock_unregister_single(bank->base_id + i);
382 if (!tmp)
383 return -EBUSY;
384
385 /* self-sanity check that should never fail */
386 WARN_ON(tmp != hwlock);
387 }
388
389 return 0;
390}
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800391EXPORT_SYMBOL_GPL(hwspin_lock_unregister);
392
393/**
394 * __hwspin_lock_request() - tag an hwspinlock as used and power it up
395 *
396 * This is an internal function that prepares an hwspinlock instance
397 * before it is given to the user. The function assumes that
398 * hwspinlock_tree_lock is taken.
399 *
400 * Returns 0 or positive to indicate success, and a negative value to
401 * indicate an error (with the appropriate error code)
402 */
403static int __hwspin_lock_request(struct hwspinlock *hwlock)
404{
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300405 struct device *dev = hwlock->bank->dev;
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800406 struct hwspinlock *tmp;
407 int ret;
408
409 /* prevent underlying implementation from being removed */
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300410 if (!try_module_get(dev->driver->owner)) {
411 dev_err(dev, "%s: can't get owner\n", __func__);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800412 return -EINVAL;
413 }
414
415 /* notify PM core that power is now needed */
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300416 ret = pm_runtime_get_sync(dev);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800417 if (ret < 0) {
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300418 dev_err(dev, "%s: can't power on device\n", __func__);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800419 return ret;
420 }
421
422 /* mark hwspinlock as used, should not fail */
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300423 tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock_to_id(hwlock),
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800424 HWSPINLOCK_UNUSED);
425
426 /* self-sanity check that should never fail */
427 WARN_ON(tmp != hwlock);
428
429 return ret;
430}
431
432/**
433 * hwspin_lock_get_id() - retrieve id number of a given hwspinlock
434 * @hwlock: a valid hwspinlock instance
435 *
436 * Returns the id number of a given @hwlock, or -EINVAL if @hwlock is invalid.
437 */
438int hwspin_lock_get_id(struct hwspinlock *hwlock)
439{
440 if (!hwlock) {
441 pr_err("invalid hwlock\n");
442 return -EINVAL;
443 }
444
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300445 return hwlock_to_id(hwlock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800446}
447EXPORT_SYMBOL_GPL(hwspin_lock_get_id);
448
449/**
450 * hwspin_lock_request() - request an hwspinlock
451 *
452 * This function should be called by users of the hwspinlock device,
453 * in order to dynamically assign them an unused hwspinlock.
454 * Usually the user of this lock will then have to communicate the lock's id
455 * to the remote core before it can be used for synchronization (to get the
456 * id of a given hwlock, use hwspin_lock_get_id()).
457 *
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300458 * Should be called from a process context (might sleep)
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800459 *
460 * Returns the address of the assigned hwspinlock, or NULL on error
461 */
462struct hwspinlock *hwspin_lock_request(void)
463{
464 struct hwspinlock *hwlock;
465 int ret;
466
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300467 mutex_lock(&hwspinlock_tree_lock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800468
469 /* look for an unused lock */
470 ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock,
471 0, 1, HWSPINLOCK_UNUSED);
472 if (ret == 0) {
473 pr_warn("a free hwspinlock is not available\n");
474 hwlock = NULL;
475 goto out;
476 }
477
478 /* sanity check that should never fail */
479 WARN_ON(ret > 1);
480
481 /* mark as used and power up */
482 ret = __hwspin_lock_request(hwlock);
483 if (ret < 0)
484 hwlock = NULL;
485
486out:
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300487 mutex_unlock(&hwspinlock_tree_lock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800488 return hwlock;
489}
490EXPORT_SYMBOL_GPL(hwspin_lock_request);
491
492/**
493 * hwspin_lock_request_specific() - request for a specific hwspinlock
494 * @id: index of the specific hwspinlock that is requested
495 *
496 * This function should be called by users of the hwspinlock module,
497 * in order to assign them a specific hwspinlock.
498 * Usually early board code will be calling this function in order to
499 * reserve specific hwspinlock ids for predefined purposes.
500 *
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300501 * Should be called from a process context (might sleep)
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800502 *
503 * Returns the address of the assigned hwspinlock, or NULL on error
504 */
505struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
506{
507 struct hwspinlock *hwlock;
508 int ret;
509
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300510 mutex_lock(&hwspinlock_tree_lock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800511
512 /* make sure this hwspinlock exists */
513 hwlock = radix_tree_lookup(&hwspinlock_tree, id);
514 if (!hwlock) {
515 pr_warn("hwspinlock %u does not exist\n", id);
516 goto out;
517 }
518
519 /* sanity check (this shouldn't happen) */
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300520 WARN_ON(hwlock_to_id(hwlock) != id);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800521
522 /* make sure this hwspinlock is unused */
523 ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
524 if (ret == 0) {
525 pr_warn("hwspinlock %u is already in use\n", id);
526 hwlock = NULL;
527 goto out;
528 }
529
530 /* mark as used and power up */
531 ret = __hwspin_lock_request(hwlock);
532 if (ret < 0)
533 hwlock = NULL;
534
535out:
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300536 mutex_unlock(&hwspinlock_tree_lock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800537 return hwlock;
538}
539EXPORT_SYMBOL_GPL(hwspin_lock_request_specific);
540
541/**
542 * hwspin_lock_free() - free a specific hwspinlock
543 * @hwlock: the specific hwspinlock to free
544 *
545 * This function mark @hwlock as free again.
546 * Should only be called with an @hwlock that was retrieved from
547 * an earlier call to omap_hwspin_lock_request{_specific}.
548 *
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300549 * Should be called from a process context (might sleep)
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800550 *
551 * Returns 0 on success, or an appropriate error code on failure
552 */
553int hwspin_lock_free(struct hwspinlock *hwlock)
554{
Wei Yongjune3526142012-09-10 12:52:02 +0800555 struct device *dev;
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800556 struct hwspinlock *tmp;
557 int ret;
558
559 if (!hwlock) {
560 pr_err("invalid hwlock\n");
561 return -EINVAL;
562 }
563
Wei Yongjune3526142012-09-10 12:52:02 +0800564 dev = hwlock->bank->dev;
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300565 mutex_lock(&hwspinlock_tree_lock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800566
567 /* make sure the hwspinlock is used */
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300568 ret = radix_tree_tag_get(&hwspinlock_tree, hwlock_to_id(hwlock),
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800569 HWSPINLOCK_UNUSED);
570 if (ret == 1) {
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300571 dev_err(dev, "%s: hwlock is already free\n", __func__);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800572 dump_stack();
573 ret = -EINVAL;
574 goto out;
575 }
576
577 /* notify the underlying device that power is not needed */
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300578 ret = pm_runtime_put(dev);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800579 if (ret < 0)
580 goto out;
581
582 /* mark this hwspinlock as available */
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300583 tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock_to_id(hwlock),
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800584 HWSPINLOCK_UNUSED);
585
586 /* sanity check (this shouldn't happen) */
587 WARN_ON(tmp != hwlock);
588
Ohad Ben-Cohen300bab92011-09-06 15:39:21 +0300589 module_put(dev->driver->owner);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800590
591out:
Juan Gutierrez93b465c2011-09-06 09:30:16 +0300592 mutex_unlock(&hwspinlock_tree_lock);
Ohad Ben-Cohenbd9a4c72011-02-17 09:52:03 -0800593 return ret;
594}
595EXPORT_SYMBOL_GPL(hwspin_lock_free);
596
597MODULE_LICENSE("GPL v2");
598MODULE_DESCRIPTION("Hardware spinlock interface");
599MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");